Piotr Esden-Tempski of 1Bitsquared created this Open Source and Open Hardware debuggable ARM development platform:
1Bitsy
Firmware development with the lights on
Design files and source code are shared on GitHub:
1bitsy-hardware
Small breadboard friendly STM32 (eventually other mcu’s too) eval boards with exposed JTAG and SWD for the use with Black Magic Probe and others!
OSH Park 